Romero made his senior league debut for Cerro Porteño on 15 May 2011, playing the full 90 minutes in a 1–0 loss to General Caballero.[3]
Corinthians
On 3 June 2014, it was reported that Romero would be transferred to Brazil's Sport Club Corinthians Paulista where he would sign a five-year contract.[4]
San Lorenzo
On 8 August 2019, he signed with San Lorenzo for three seasons.[5] On 31 August, he scored his first goal for the club, in a 2–1 victory over Unión, in a match valid for the Argentine Championship.[6] On 18 August 2020, Romero injured teammate Andrés Herrera, causing a fracture of his leg. The tackle was heavily criticized by teammates, and Romero was made to train separate from the team by manager Mariano Soso.[7][8] On 28 August 2021, the club announced the termination of the contract with Romero in order to comply with the Financial Fair Play implemented by the LPF.[9]
Cruz Azul
On 2 February 2022, he was announced by Cruz Azul, with a contract valid until December 2022.[10]